U.S. Southern Command has joined efforts to help the Argentina Navy find a missing submarine that was carrying 44 crew members when it disappeared off the country’s southern coast on Wednesday.

On Saturday, Southcom directed the U.S. Navy to deploy a P-8A Poseidon multi-mission maritime aircraft to Bahia Blanca, Argentina, to help find the A.R.A. San Juan, a German-built, diesel-electric vessel that was first commissioned in 1985 and retrofitted in 2014.

A second U.S. Navy P-8A Poseidon aircraft will deploy to Bahia Blanca, Argentina, on Sunday join the search.

Southcom is responsible for guiding U.S. military operations in the Caribbean, Central American and South America.

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The aircraft and its 21-person crew are heading for Argentina from El Salvador’s Comalapa Air Base, where the P-8A Poseidon was supporting counter-illicit trafficking maritime patrol operations. Once in Bahia Blanca, the crew will join the ongoing international search at the request of the Argentina government.

The P-8A Poseidon is a relatively new Navy maritime, patrol and reconnaissance aircraft configured with state-of-the-art sensors and communications equipment. The vessel went into operation in November 2013, and is designed to support a wide range of missions over large bodies of water, including sub-surface search-and-rescue operations.

According to the U.S. Navy, the Poseidon can reach an airspeed of 564 mph, has a ceiling of 41,000 feet and a range of 1,200 nautical miles with four hours on station, allowing it to loiter over search areas. The Poseidon is armed with torpedoes and cruise missiles. The P-8A provides more combat capability from a smaller force and less infrastructure while focusing on worldwide responsiveness.

U.S. Navy aviators perform preflight checks in the flight station of the P-8A Poseidon prior to a mission on April 1, 2014, from Perth, Australia, to assist in search and rescue operations for Malaysia Airlines flight MH370.
KEITH DEVINNEY
AFP/Getty Images

The U.S. Navy also deployed the San Diego-based Undersea Rescue Command to help with the search efforts.

At URC’s disposal: the Submarine Rescue Chamber, which can reach depths of 850 feet and rescue up to six people at a time, and the Pressurized Rescue Module, which can submerge up to 2,000 feet and rescue up to 16 at a time. The former is scheduled to arrive in Argentina on Sunday, and the latter should arrive early next week.

On Friday, Enrique Balbi, a spokesman for the Argentine Navy, told The Associated Press that there was a possibility that the sub had some kind of electrical issue and might not be missing. He said he didn’t want to sound “alarmist,” but noted then that there had been no communications for two days, “even with the alternative methods that the submarine has.”

But on Saturday, as the country reached out for help, the tone had changed.

“The submarine knows that if it does not have communication with land for this long, it has to surface,” Balbi told CNN.

The search has resonated in the Vatican. Pope Francis, an Argentina native and a former archbishop of Buenos Aires, offered his “fervent prayers” for the safety of the 44 officers aboard the ARA San Juan in his message Saturday, CNN reported.

Francis asked “that his closeness be conveyed to their families and to the military and civil authorities of the country in these difficult moments,” the message read.

The P-8A Poseidon aircraft recently conducted overflight assessment missions after Hurricane Maria lashed the Caribbean in September. The Poseidon captured images of devastation in Dominica to help support U.S. foreign disaster assistance operations.